An electric discharge treatment technology is known in which a chemical substance (s) is treated by generating electric discharge within a predetermined space. In the field of water treatment, an electric discharge treatment technology is under consideration in which a decomposition resistance substance (s) is removed with a high degree of efficiency by directly operating hydroxyl radicals produced by electric discharge on water to be treated.
Patent Document 1 proposes a water treatment apparatus using an electric discharge treatment technology. The water treatment apparatus of Patent Document 1 includes a reaction-vessel or reactor having therein inclined plates for flowing down treatment target water, treatment means in hierarchical structure having electrodes each for generating electric discharge thereacross to perform treatment by radicals produced by electric discharge with respect to the treatment target water, and a pulse discharge power-supply means for applying a short-pulse high-voltage with respect to the electrodes. In a system using the water treatment apparatus of Patent Document 1, it becomes possible to decompose decomposition resistance substances dissolved in water by utilizing radicals produced by means of streamer discharge.
Patent Document 2 proposes an exhaust gas treatment apparatus using an electric discharge treatment technology. A purification apparatus of Patent Document 2 includes a casing having electrodes for generating electric discharge thereacross for performing treatment by radicals produced by electric discharge with respect to a treatment target gas(es), and a high-voltage very short pulse power-supply with respect to the electrodes for applying a high voltage. In a system using the purification apparatus of Patent Document 2, it becomes possible to decompose gas-state contaminated substances by means of corona discharge.
In the electric discharge treatment technologies described above, electric discharge is generated by applying a voltage across the electrodes using a pulse discharge power supply. In accordance with the electric discharge being generated, radicals of ozone (O3), hydroxyl radicals (OH radicals) or the like are produced. By giving rise to the reaction of radicals being produced with a substance(s) to be treated, the treatment for decomposing the substance(s) to be treated is carried out. In a case in which treatment efficiency of a substance to be treated is increased by using an electric discharge treatment technology, an appropriate support measure is conceivable in which, in order to achieve increasing the amount of supply of radicals into the substance to be treated, a voltage being applied from a pulse discharge power supply is raised so that electric power being entered is increased. While on the other hand, an appropriate support measure is conceivable in which a repetition frequency of pulse discharge is raised so that the entered electric power is increased.